Add guide for contributing to project
Add guide for contributing to project

RavnSystems/ews-java-api,arielnetworks/ews-java-api,KatharineYe/ews-java-api,relateiq/ews-java-api,AFaust/ews-java-api,candrews/ews-java-api,easel/ews-java-api,mattguo/ews-java-api,evpaassen/ews-java-api,mattguo/ews-java-api,casimirenslip/ews-java-api-ms,SpanningCloudApps/ews-java-api,ahaarrestad/ews-java-api,kentongray/ews-java-api,ebf/ews-java-api,Sealinune/ews-java-api,serious6/ews-java-api,xvronny/ews-java-api,kentongray/ews-java-api,avromf/ews-java-api,candrews/ews-java-api,avromf/ews-java-api,kaaaaang/ews-java-api,sanjay444/ews-java-api,eveoh/ews-java-api,SpanningCloudApps/ews-java-api,KatharineYe/ews-java-api,sanjay444/ews-java-api,easel/ews-java-api,Sealinune/ews-java-api,cfraser/ews-java-api,wwahmed/ews-java-api,RavnSystems/ews-java-api,ebf/ews-java-api,serious6/ews-java-api,7thsense/ews-java-api,chianquan/ews-java-api,chianquan/ews-java-api,pheenomenon/ews-java-api,cfraser/ews-java-api,piraengu/ITcode,wwahmed/ews-java-api,OfficeDev/ews-java-api,casimirenslip/ews-java-api-ms,AFaust/ews-java-api,pheenomenon/ews-java-api,govind487/pa-ewsapi-3.0,travisc5/ews-java-api,7thsense/ews-java-api,relateiq/ews-java-api,OfficeDev/ews-java-api,travisc5/ews-java-api,piraengu/ITcode,xvronny/ews-java-api,ahaarrestad/ews-java-api